Armor penetration resistance enhancement

ABSTRACT

A metal cup encloses layers of armoring material to enhance the penetrationesistance of a guided missile warhead to mechanical countermeasures. A layer of ceramic material is inserted in the cup followed by the insertion of at least one pair of layers consisting of a layer of metal backed by a layer of polymethylmethacrylate. The metal cup is attached to the forward end of a missile warhead section and the exterior of the cup is conformal with respect to the exterior of the warhead section. The layered materials act to blunt or break incoming projectiles, absorb their kinetic energy, and prevent their penetration into the interior of the warhead.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to armoring material and an arrangementthereof. More particularly, this invention relates to an arrangementincorporating armoring material to enhance the resistance of a longrange land or surface attack guided missile warhead section topenetration and destruction by mechanical countermeasures such as gunprojectiles.

2. Description of the Prior Art

Currently, protection of guided missile warhead sections from mechanicalcountermeasures involves the thickening of the forward facing end of themetal encasement which forms the warhead section and encloses thewarhead explosive. By way of background it is useful to note that inmany guided missile configurations the warhead section is not theforwardmost section of the missile. Oftentimes a guidance, control orother section is located forward of the warhead. At the range at whichmechanical countermeasures, such as gun shells, can be expected to beencountered "head-on" by a long range missile the sections of themissile forward of the warhead have essentially accomplished their taskof bringing the warhead to a target. At this point in the flight of themissile, protection of the warhead and its fuzing becomes the paramountconcern. As noted, warhead protection currently relies on the thickeningof the forward end of the warhead encasement. Where the warhead is notthe forwardmost section of a missile, the forward end of the warheadencasement must also accommodate the mounting of the missile sectionforward of it.

The degree of protection from mechanical countermeasures offered by athickened forward encasement end has heretofore been a function of theamount of thickening which could be tolerated in terms of added weightto the missile. As warhead encasements are generally fabricated fromsteel, encasement thickening rapidly adds a significant amount of weightto the missile where the facial area of the warhead encasement can be onthe order of 300 square inches or more. While a thickened encasement mayprovide adequate protection for the warhead from mechanicalcountermeasures, the thickening may result in a significant loss inmissile range due to the added weight. As a result, a design tradeoffmust be made in current guided missiles between the need to provide thewarhead protection from mechanical countermeasures and the need topropel that warhead over long distances. A need thus exists to provideadequate protection to guided missile warheads while not, in the processof providing such protection, adding an amount of weight whichsignificantly reduces the range of the missile.

SUMMARY OF THE INVENTION

The present invention solves the problem of providing a guided missilewarhead adequate protection from mechanical countermeasures while addinga tolerable amount of weight to the missile structure. As a result, therange of a missile is essentially unaffected while warhead protectionand penetration resistance is enhanced. A layered combination ofmaterials is retained in an enclosure which is attached to the forwardend of a warhead encasement. The warhead encasement need not bethickened for the purpose of protecting warhead components although somethickening is still an option. The majority, by volume, of layer formingmaterials are lightweight as compared to an equivalent thickness ofsolid metal yet the arrangement provides essentially the same orimproved resistance to penetration by mechanical countermeasure thanwould a similar thickness of metal.

It is an object of the invention to provide enhanced protection to aguided missile warhead from mechanical countermeasures.

It is a further object of the invention to provide enhanced guidedmissile warhead protection by the use of armoring materials which arecapable of blunting, breaking and stopping countermeasure projectiles orfragments before the countermeasure is able to destroy or damage thewarhead.

Still a further object of the invention is to provide armored protectionto a guided missile warhead which does not appreciably add to the weightof the overall guided missile structure.

The nature of this invention as well as other objects and advantagesthereof will be readily apparent from consideration of the followingspecification as related to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a long range guided missiledemonstrating a typical arrangement of component sections; and

FIG. 2 is a one-quarter cutaway perspective view of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The armoring arrangement of the present invention provides enhancedresistance to penetration and destruction by a projectile to a guidedmissile warhead at an acceptably small increase in overall missileweight. It has been determined that when a layer of metal armor isbacked by a layer of polymethylmethacrylate the penetration resistanceof the combination is enhanced at little increase in weight. Similarly,it has been found that a lesser thickness of metal backed by a layer ofpolymethylmethacrylate will provide essentially the same and possiblybetter penetration resistance as compared to a thicker and much heavierunbacked thickness of metal armor. Still further enhancement in theamount of protection provided a warhead from mechanical countermeasureimpact is accomplished when a layer of ceramic material is placedforward of at least one layered combination of metal armor backed bypolymethylmethacrylate. The ceramic layer blunts an impinging projectileand can cause the projectile to break into fragments.

In sequence then, a projectile which encounters a thickness of ceramic,the ceramic preferably being aluminum oxide, will be blunted or brokenupon impact. This impact significantly reduces the kinetic energy of theprojectile or its fragments. The projectile or fragments upon nextencountering a layer of metal, preferably high strength steel, will befurther broken up and will lose an additional amount of kinetic energy.Unlike the brittle ceramic the metal layer will not tend to break butwill tend to hold together absorbing significant amounts of kineticenergy while preventing further penetration toward the interior of thewarhead. Each fragment or a projectile which accomplishes thepenetration of the metal layer next encounters a layer ofpolymethylmethacrylate. This material exhibits a high degree ofresistance to penetration and while it may undergo significantdeformation at an impact point, complete penetration of thepolymethylmethacrylate layer is unlikely. Further penetration resistanceis achieved by the use of additional layers of metal each of which isbacked by a layer of polymethylmethacrylate. The number of layers addedis constrained only by the available volume in which to accommodate thematerial and the amount of added weight which can be tolerated.

The mode of the invention deemed most advantageous to the protection ofa guided missile warhead includes the use of a metal cup to enclose thelayers of material mentioned above. The preferred metal is a highstrength steel although other metals or alloys may be utilized. The useof a cuplike enclosure is advantageous in several respects. The closedend of the cup forms a first metal bulkhead which a projectile mustpenetrate in order to reach the warhead. Additionally, the closed end ofthe cup can easily be configured to accommodate the attachment of amissile section forward of it and the open end of the cup is easilyconfigured to be attached to the forward end of existing warheadsections which are configured for the attachment of forward missilesections.

Referring now to FIG. 1, a typical long range guided missile 2 is shownin perspective. The missile illustrated includes a nose section 4, aguidance or control section 6, and a motor section 8. Warhead encasement10 with armoring cup 18 is shown mounted between guidance or controlsection 6 and motor section 8.

Referring now to FIG. 2, an armoring arrangement of the presentinvention is illustrated attached to a warhead. Existing metal warheadencasement 10 which contains explosive 12 has a forward encasementbulkhead 14 having a mounting lip 16. Cylindrical metal armoring cup 18has a closed end which forms forward cup bulkhead 20 and an open aft end22. Forward cup bulkhead 20 has a mounting lip 24 which in mostinstances will be dimensionally identical to mounting lip 16 ofencasement 10. Open aft end 22 of cup 18 fits onto mounting lip 16 ofencasement 10 to accommodate the rigid and secure attachment of cup 18to encasement 10. FIG. 1 demonstrates the attachment of cup 18 toencasement 10 by use of machine screws 30. Any number of other standardfasteners could be used for this purpose. The use of a crimping processto attach cup 18 to encasement 10 has been suggested as has thepossibility of heating cup 18 prior to its attachment and allowing it toshrink onto encasement 10 as it cools. When cup 18 is attached toencasement 10 exterior surface 26 of cup 18 is conformal with respect toexterior surface 28 of encasement 10.

Prior to the installation of cup 18 on encasement 10 several layers ofmaterial are inserted into cup 18. First, a layer of ceramic material 32is inserted into cup 18. Ceramic layer 32 is dimensioned to fit snuglyinto cup 18 and abuts the internal face of forward cup bulkhead 20.After ceramic layer 32 is inserted, metal plate 34 is inserted into cup18. Metal plate 34 fits snugly into cup 18 and abuts ceramic layer 32. Alayer of polymethylmethacrylate 36 is inserted into cup 18 after metalplate 34. Polymethylmethacrylate layer 36 fits snugly into cup 18 andabuts metal plate 34. Additional pairs of layered meterials such asmetal plate 38 and polymethylmethacrylate layer 40 may then be insertedinto cup 18 depending upon volumetric and weight constraints.

As previously noted, while many metals can be utilized in fabricatingthe structure of a guided missile, the use of a high strength steel toform encasement 10, cup 18, and metal plates 34 and 38 has proven to behighly satisfactory.

The use of an adhesive at interfaces 42A, 42B, 42C, 42D, and 42E, and atany other such interface formed by the addition of more layers of metalbacked by polymethylmethacrylate, is optional and may be advantageous tobond the various layers of material into cup 18 and to each other.

It may also be advantageous or necessary to include a spacer layer 44between the final layer of polymethylmethacrylate and the outside faceof forward encasement bulkhead 14 of encasement 10 to fill any voidwhich might otherwise exist at that location after cup 18 is attached toencasement 10. The use of a feltlike compressible material iscontemplated in this regard.

Many modifications and variations of the present invention are obviousin light of the above teachings and it is therefore to be understoodthat within the scope of the appended claims the invention may bepracticed otherwise than as specifically described.

We claim:
 1. A construction to enhance the survivability of a guidedmissile warhead against mechanical countermeasures, which comprises:acylindrical metal armoring cup having an open aft end and a closedforward end which forms a forward bulkhead; a ceramic layer insertedinto said cup, said ceramic layer dimensioned to fit snugly into saidcup and to abut said forward bulkhead; a metal plate inserted into saidcup, said metal plate dimensioned to fit snugly into said cup and toabut said ceramic layer; a layer of polymethylmethacrylate inserted intosaid cup, said polymethylmethacrylate layer dimensioned to fit snuglyinto said cup and to abut said metal plate; and means for attaching saidopen aft end of said cup to the end of said warhead which is to beoriented toward a target at which said warhead is to be launched.
 2. Aconstruction according to claim 1 wherein said ceramic layer is a layerof aluminum oxide.
 3. A construction according to claim 1 wherein saidmetal armoring cup is a steel cup; and, said metal plate is a steelplate.
 4. A construction according to claim 1 wherein said ceramic layeris bonded to said metal cup by an adhesive; said metal plate is bondedto said ceramic layer by an adhesive; and, said layer ofpolymethylmethacrylate is bonded to said metal plate by an adhesive. 5.A construction to enhance the survivability of a guided missile warheadagainst mechanical countermeasures, which comprises:a cylindrical metalarmoring cup having an open aft end and a closed forward end which formsa forward bulkhead; a ceramic layer inserted into said cup, said ceramiclayer dimensioned to fit snugly into said cup and to abut said forwardbulkhead; a first metal plate inserted into said cup, said first metalplate dimensioned to fit snugly into said cup and to abut said ceramiclayer; a first layer of polymethylmethacrylate inserted into said cup,said polymethylmethacrylate layer dimensioned to fit snugly into saidcup and to abut said first metal plate; at least one additional metalplate inserted into said cup; an additional layer ofpolymethylmethacrylate inserted into said cup after the insertion ofeach additional metal plate; and means for attaching said open aft endof said cup to the end of said warhead which is to be oriented toward atarget at which said warhead is to be launched.
 6. A constructionaccording to claim 5 wherein said metal armoring cup is a steel cup;said first metal plate is a steel plate; and, each additional metalplate is a steel plate.
 7. A construction according to claim 5 whereinsaid ceramic layer is a layer of aluminum oxide.
 8. A constructionaccording to claim 5 wherein said ceramic layer is bonded to said metalarmoring cup by an adhesive; said first metal plate is bonded to saidceramic layer by an adhesive; said first layer of polymethylmethacrylateis bonded to said first metal plate by an adhesive; and, each of saidadditional metal plates is bonded by an adhesive to the layers ofpolymethylmethacrylate between which it is located.
 9. A constructionaccording to claim 5 wherein:said ceramic layer has a thickness of fromone-quarter to one-half of one inch; said metal plates have a thicknessof from one-tenth to one-quarter of one inch; and said layers ofpolymethylmethacrylate have a thickness of from one-quarter of one inchto one inch.
 10. A construction according to claim 6 wherein:said layerof aluminum oxide has a thickness of from one-quarter to one-half of oneinch; said steel plates have a thickness of from one-tenth toone-quarter of one inch; and said layers of polymethylmethacrylate havea thickness of from one-quarter of one inch to one inch.